Measurement and control of the flow of viscous fluids



Nov. 28, 1939.` H. G. GEISSINGER v 2,181,322

MEASUREMENT AND CONTROL OF THE FLOW 0F VISCOUS FLUIDS Original FiledAug. '23, 1934 l y M ATTORNEYS. l

Patented Nov. 28, 1939 UNITED STATES MEASUREMENT AND CONTROL OF THE FLOWOF VISCOUS FLUIDS Harry G. Geissinger, Cleveland, Ohio Originalapplication August 23, 1934, Serial No. 741.173. Divided and thisapplication January 25, 1937, Serial N0. 122,251

Claims.

My invention relates to the measurement and control of the ow of viscousfluids, and this application is a division of my co-pending application,Serial No. 741,173, filed August 23, 1934 now Patent No. 2,072,204.

The primary object of the present invention is to provide animprovedmethod and apparatus 4 for controlling oil burning equipment for indus--trial furnaces.

Other objects will be more apparent as 'the description proceeds.

In the drawing: Figure 1 is a'sectional plan view of a fuel input valveembodying one form of my invention; l5 Figure 2 is a vertical section onthe line 2-2 of Figure 1;

Figure 3 is a' vertical section on the line 3-3 of Figure l;

Figure 4 is a top planview of a portion of the appazratus as indicatedby' the line H of Figure Figure 5 is a vertical section at right anglesto the section shown in Figure 2 and is taken on the line 5-5 of Figure4; Figure 5A is a fragmentary vertical section on line 5A-5A of Figure4;

Figure 6 is a sectional view on a smaller scale takenon line 6-6 ofFigure 1;

Figure 7 is a diagram showing the device of Figure 1 connected to afurnace system;

Figure 8 is a longitudinal section through an equalizer burner valve;

Figure9 is a fragmentary section of the lefthand portion of the deviceshown in Figure 2 showing a modified form of throttling valve control;

Figure l0 is a section onthe line |0--I0 of Figure 3.

'I'he invention as illustrated is in the form of a 40 fuel input valveadapted to deliver oil to a burner system `determined by the square rootof the pressure offthe combustion air supplied to the burners. Theconstruction is of the same general type as illustrated in Figure 6 ofmy co- 55 Thus the partition wall I4 is retained in the cap pendingapplication, but is provided with addi-- by the annular sleeve |2| whichthreadedly engaging the boss and having the head end thereof at theupper end of the cap 43 as illus- 5 trated in Figure 5. The metering pinl5 is secured tothe cup-shaped member by fasten'ng means |23. Thediaphragm system 9d, I0, 8 is also similar to that shown in my PatentNo. 2,072,204 except that the diaphragm 20d is now omitted.

The inlet 2 is provided with a ball valve 34 and seat 35, and the valveis operated by a lever 32 which is connected to an auxiliary diaphragm36. The casing I is provided with a partition wall |5| forming an inletchamber |52 into which the iiuid from theinlet 2 first passes. Thediaphragm 36 has one side thereof subjected to the pressure in the inletchamber |52 and is secured to the casing by a cap |53 forming a chamberI |54 on the opposite side of the diaphragm. A passageway |55 connectsthe chamber |54 with the central cavity ||8 thereby equalizing thepressures in these chambers. Communication between the inlet chamber |52and the central ,I cavity ||8 is provided by means of the pressure valve31 which, as shown, comprises a tube |56 extending through the partitionwall |5| and having a series of radial ports |51. A slidabl sleeve |58is arranged Within the tube |56 and is 3 adapted to move within the tubeby means of' the lever |59 which in turn is freely mounted on the shaft40. 'I'he outer end of the lever |59 carries a pin 38 adapted to contactwith the center plate of the diaphragm 9d. A spring 39 fixedly g securedto the shaft 4|) bears against the pin 38 and holds the latter incontact with the center plate of the diaphragm. The shaft 40 extendsoutwardly through the casing I and has iixedly secured `thereto a lever4| which in turn abuts a push rod 42 extending longitudinally beneaththe casing. The push rod 42 is adapted to be moved in accordance withthe pressure of the air supply or by any other suitable controllingforce and the preferred construction will now be described.

The cap |60 which retains the diaphragm 8d in position on the casing hasa plurality of lugs 54 extending outwardly therefrom. A ring |62 ismounted on' the lugs. A diaphragm |63 ex- 50 tends across the ring |62and is retained in position by a cap |64 and retaining screws I6| whichthreadedly engage the lugs 54. The cap |64 is recessed forming a chamber|65 on one side of the diaphragm |63 into which air under pressure mayenter through the port 55. The lugs 56 are ,grooved to receive thecircumference of a split ring 52. The ring terminates at one end in alug |66 having a threaded aperture for'receiving a threaded pin 53. Theother end of the ring has a laterally extending portion |61 terminatingin the lug |68, spaced from the lug |66 and having an aperture |69 forreceiving the end of the pin 53.` Thus by adjusting the threaded pin 53the lugs |66 and |68 may be spread thereby frictionally engaging thering 52 in the grooved lugs 54. 5| is a hinge arranged between the lugs|66 and |68 and using the pin 53 for its pivot. Extending from the hingeis a member 50 which extends in alignment with the center of thediaphragm |63 and has a return bent portion |10 of arcuate shape. Thecenter plate of the diaphragm |63 `has a projecting portion |1| adaptedto bear against the member 50. The push rod 42 hereinbefore describedabuts the arcuate member |10.

With the adjustable hinged arrangement as described, it will be observedthat by loosening the threaded pin 53 the ring 52 may be rotatablyadjusted in the lugs 54 thereby rotatably adjusting the hinge 5| andconsequently changing theA effective leverage on the push rod 42. Withthe.

parts in the position as illustrated, the effective leverage on thediaphragm |63 and the push rod 42 is the same, but by adjusting thehinge rotatively, the leverage effective on the push rod 42 is increasedor decreased over that eiectize on the diaphragm. This adjustment makesit possible to compensate for differences in combustion air pressures inthe initial setting of the apparatus.

On the cap |64 is arranged a proportioning valve |12 adapted todetermine the air pressure in the chamber |65. As shown, this comprisesa cylinder |13 having two conduits communicating therewith designated 58and 59. A piston 60 within the cylinder is so arranged as tosimultaneously uncover aportion of each of the conduits and permitcommunication with the recessed -intermediate portion |14 of the piston.The aperture 51 in the cap also communicates with this recessed portionof the piston. An adjustment screw 62 is adapted to move the piston tovary the proportion of the fluid entering the proportioning valve.

In order to clear the central cavity ||.8 of accumulation of gases asuitable vreliefvalve is provided. As shown, the cap 43 is provided witha shouldered vertical passage |15 extending from the cavity I8 into thepassageway 15. The passageway 15, as in the preceding examples, ex-

tends between the chamber P on the outside of the minor diaphragm 8d andthe chamber O above the orifice 4, and consequently communicatesdirectly with the discharge 3 by means of the down-turned passageway|16. The valve 45 is actuated by means of a lever 46 arranged within thecentral cavity ||8 and pivoted on the pin 48. The other end of the lever46 is provided with a float 41, the arrangement being such that wheneverthe liquid level falls through an accumulationof gases, the valve 45 isopened and permits such gases to escape through the port 15 and thedischarge 3.

There is also provided a manually adjustable by-pass from the cavity H8,this being in the form of an adjustable screw-44, the head of whichextends through the top of the cap. The lower end of the screw forms avalve cooperating with the conical valve seat |11 to close or open anauxiliary vertical passageway |18. The upper end slight uctuations.

mais@ uid enters through port 2, flows past ball valve 34 into the inletchamber |52 and then passes through the pressure valve 31 into thecentral cavity H8. The -uid then passes downwardly through the variablechannels |26 of the resistor into the cup-shaped member |22, thenupwardly through the channels |30 of the resistor. It then flows throughthe orice 4 into the chamber O and out through the discharge 3. 'I'hisow of iiuid creates a tension in the diaphragm system 8d, I0', 9d in thedirection of the arrow |05, that is, towards the minorv diaphragm 8d.This pressure is then transmitted through the spring 39 to the rod 40and tends'to oscillate the same in one direction. This oscillation,however, is resisted by the force transmitted to the rod 40 by the lever4| and push rod 42 which, as previously explained, is derived fromA theair pressure acting on the diaphragm |63. Thus the pressure due to theliquid iiow and the pressure obtained from the air flow are balancedagainst each other through the spring 39 Which tends to eliminate The'free lever |53 which actuates the pressure valve 31 is also responsiveto the movement due to the balanced forces above mentioned since the pin38 attached thereto is intermediate the diaphragm 9d and the spring 39,and therefore exerts a throttling effect between the chamber |52 and thecavity ||8. This in turn creates a diierential pressure on the dia.-

-phragm 36 and actuates thelever 32 to open or Figure 7 -illustratesdiagranmiatically a pre- 'erred method of utilizing the fuel input valvejust described in connection with automatic temperature controlmechanism of a metallurgical furnace. It also illustrates two differenttypes of oil burners and the association with a motorized air controlenergized and directedv by thermometric instruments. The instrumentsthemselves are not illustrated, nor is the furnace, since they may be ofany suitable type and are not essential to the understanding of theinvention.

The combustion air enters through the trunk line 63 from a suitablesource and is distributed to the burner 66 through a branch pipe |80 andto burner 66a through branch I8 I. The oil enters the casing of my fuelinput valve through the inlet 2 and leaves through the discharge 3,being distributed to the burner 66 by a conduit |82, equalizer burnervalve 69 and conduit 13. It is similarly distributed to lburner 66a byconduit |83, equalizer burner valve 69 and conduit 13. The trunk line 63is provided with a valve 64 mechanically operated by suitable mechanismnot illustrated in detail but diagrammatically represented at 65. Thisform of motor controlled valve is well understood in theart, and theposition of the valve is determined by thermometric instruments in themetallurgical furnace.

An air line conduit 61 communicates with the trunk line in advance ofthe valve 64 and is provided with a manually operable valve 68. Onebranch from the conduit 61 is connected to the pipe 58 of theproportioning valve previously described. The other pipe 59 of theproportioning valve is connected to the branch air line line pressureand the'pressure of the air flowing' to theburner. 'I'his proportion'may be suitably adjusted by changes of the area of the ports covered bythe valve 6 0 of the proportioning valve.

' The equalizer burner valve 69 is shown in detail in Figure 8. Itcomprises a cylinder |84 in which a piston |85 is longitudinallyadjustable by means of a threaded stem |86 engaging the correspondinglythreaded head |81. The piston has a spiral groove |88 in the peripherythereof through which the oil is required to fiow from the annularchannel |89 to the discharge orice |90. By rotatably adjusting thepiston |85 through the handle |9|, the length of the spiral groovebetween the inlet and discharge may be` varied, consequently varying theresistance to the passage of the oil. 12 is a shut-off valve.

In order to understand the operation of the system as illustrated inFigure 7, it should be remembered that the valve 64 will assumepredetermined positions by direction of the ther-l mometric instruments,ranging from a Wide open position during the starting of the furnace toa' closed position when the furnace ceases to bein operation.Intermediate positions of the valve will be obtained in order to exactlyregulate the amount of air delivered to the furnace under changingtemperature conditions. The quantity of oil passed by the meteringcontrol device is determined by some proportion of the combustion airpressure and is not determined solely by the pressure delivered to theburner valve 66. This isv for the reason that at times of low combustionrate in the furnace, external air flows into the furnace through burnerport's and other leakag-es. This influx tends to produce an oxidizingatmosphere. To retain the true proportion of air and fuel for idealcombustion, the arrangement which I have illustrated makes it possibleto enrich the combustion at low ring rates and to make this i enrichmentreadily controlled by the operator 'is negligible.

without permitting the operator to alter the normal combustion mixturesduring the normal firing of the furnace.

Referring again* to Figure '1, it will be apparent that if the valve 6Bwere closed, air would iiow through the pipes B1 and 58 to the proporfltioning valve and thence through pipe 59 and conduit |80 to the burner66, although the amount of ow through the proportioning valve However,there'would still be a definite pressure in the chamber |65 acting onthe-air pressure diaphragm |63 and this pressure would produce acertain. oil flow through the apparatus. It will also be noted that ifthe valve 64 were Wide open, pressures in 58 and 59 would besubstantially equal and the pressure effective on the air pressurediaphragm |63 would be the pressure of the burner system. Due to thesquare root effect of the air pressure, the enrichment adjustmentpractically disappears at a 50% to 70% fuel input. Y

In Figure '7 I have also illustrated a second type of burner 66a whichis of the dual air type. The secondary air supply is introduced througha conduit |92 from the conduit 68, which in turn receives its supply inadvance of the controlling valve 64. The secondary air supply istherefore never under the automatic control.

A modication of the device shown in Figure 2 is illustrated ih I Figure9. 'I'he only change from the devia @f Fievet 1s a ,me am p f .ne

throttling valve which replaces the diaphragm 36, lever 32 and ballvalve 34. As shown in this construction, the partition wall divides thecavity ||8 from an inlet chamber |52 as in the preceding device. Thethrottling valve 31 is the same as before but is located at a lowerportion of the chamber |52. Instead of the diaphragm 36'there 4is nowAprovided a piston |93 verticallyslidabl'e in a sleeve I 9|. A port |55establishes communication between the head of the piston and the centralcavity |8. The valve body |95 has an inlet port |96 registering with theuid inlet 2. The valve consists of a rod |91 having a threaded portion|98 engaging the valve body |95. The valve has a groove |99 therein andthe arrangement is such that rotation of the same will expose a variableamount of the 'groove and thus vary the amount of uid which can ow fromthe valve body to the chamber |52. lIhe rotation of the valveis by meansof a sprocket 200 on the end of the valve. A chain 20| passes over thesprocket and one end thereof is secured at 202 to the piston, while theotherl'end thereof is attached to a coil spring 203 which in turn issecured to the casing as indicated at 200.

In the operation of the device, fluid entering lthrough the throttlingvalve |91 passes through the pressure valve 31 which creates adifference of pressure between the chambers |52 and H8, thus moving thepiston |98 which in turn rotates the valve* |91 and varies the amount ofiiuid entering chamber |52. It will-be noted that the closing of thethrottling valve is the result of upward motion of the piston 93 inresponse to a decrease in the area of the pressure valve 31.

.This upward motion of the piston reduces the ow through the-pressurevalve, automatically reducing the effect of the same and anticipates thenew position. Such anticipation eliminates hunting in the throttlingvalve. The closing action alsol creates increase in the counter-pull ofthe spring 203 cooperating in anticipation eect. It will be notedthatvmovement of the piston |93 does not alter the flow through themetering device of the control.

The fuel input valve of the system connected thereto as illustrated, hasmany advantages over the prior art. In the rst place, the viscosityeffect is eliminated in accordance with the principles described in myPatent, 2,072,204, issued March 2, 1'937. It should also be noted thatthe throttling valve in actual control of the ow is self-cleaning,automatically opening to produce a definite fiow. The metering orificeand pase sageways are of such size throughout that granu lar carbon(which is present in all modern fuel oil) cannot clog the same incontradistinction to for controlling the oil supply. In my apparatus thequantity of fuel oil delivered to a group of burners is automaticallydetermined by the combustion air pressures whether the variationsvinpressure are accidental or produced bydirect intent. My invention meetsthe modern tendency towards' a fioating combustion rate. In conjunctionwith motorized air valves under the `present-day devices using smalltapered orifices 8|) d2 may be reduced, larger .metering systems'equalizing the output.

My device provides for the enrichment of the combustion mixture at lowcombustion. rates without affecting the adjustment under normalconditions. ing valve 62, but as previously explained, this enrichmentis enirely nullied at higher rates because of the equalization ofpressures on the opposite sides of the throttling valve 64 where thelatter is open. My device further provides izer has `a. back pressureproportioned to the ow and offers material opposition at low rates.

It should be understood that while Figure 7 shows two burners under thesame control, the

number of burners may be varied at will, depending upon the furnaceconstruction. A

It will be noted that in the construction illustrated in Figures i and2, the orifice rod I5 has a variable groove therein and the resistor ismade up of two parts, one having variable channels, and the other havingchannels of fixed dimensions.

It will be evident that the resistance factor R of the orice will varywith the area and stroke of the system, and that the factor r of theresistor must vary in proportion therewith. The resistance developed bythe channels |30 is proper-- tional to that of themaximum area of theorifice 'When the rod I5 and the cup-shaped member |22 are in theirlowermost positions, the widths of the channels |26 are developed sothat the additional resistance, due to the decreasing area of theorifice, will add a proportional resistance to the resistor system. Theraising of the rod I5 and the cup-shaped member |22 therefore bothincreases the length of the resistor and reducesthe primary area of thesystem. In order to calibrate the instrument shown in Figure 2. theadjustable core I 28, which has the xe'd resistor channels |30 therein',is adjusted longitudinally with respect to the sleeve I2I while thecup-shaped member |22 is in its uppermost position until the properproportion between the resistance of the fixed channels I30 and thevariable channels I26.is obtained,

l this proportion depending upon the maximum and minimum orifice areasdue to the extreme movement of the rod I5. When the desired proportionis obtained, the core |28 is suitably secured to the sleeve I2Ibysuitable securing means. The rod I5, which is threadedly secured tothe cupshaped member I 22, is thereupon adjusted so that theresistancefactor R is exactly proportional to the resistance factor r, the latterbeing the sum-- mation of the fixed resistance of the channels |30 andthe variable resistance of the channels |26.

apparatus which will exactly nullify the viscosity effect o'f the fiuid.It is also possible to determine these factors mathematically.-

One of the features of the 1116141119111? YQIYQ'I 'I'his is by means ofthe proportionstood that the invention is not to be considered as.

limited to the speciflc embodiments herein described, but the scope-ofthe invention is to be construed by the claims appended hereto.

What I claim as my invention is:

1-. A system for controlling combustion of -fiuid lfuel comprising aburner, an air line and a fluid fuel line connected thereto, a valve insaid air line adapted to regulate the air supply to said burner,

Va valve in said fluid fuel line. adapted to regulate the uid fuelsupply .to said burner, means for regulating said fluid fuel valve bytheunbalanc- 'ing between a pressure derived from the fluid iiow and apressurederived from said air line, conduits from said air line, onopposite' sides f said air valve connected to said fuel regulating meanswhereby air pressure anterior to said air, valve is effective on saidfuel regulating means in-order to increase the ratio of fuel to air whensaid air valve approaches the'closed position while maintaining thenormal ratio when said air valve is open.

Y 2. A system for' controlling combustion of liquid fuel comprising aburner, an air line anda liquid fuel line connected thereto, a valve insaid air line adapted'to regulate the air supply to said burner,'afvalve in said liquid fuel line' adapted to regulate the liquid fuelsupply 'to said burner, said fuel valve comprising a passageway for theliquid fuel having a constricted area. therein` and vhaving meanstherein for creating a resistance to ow which is a function of length, amovable element having pressure -responsive faces f different effectiveareas, means for urging said elementv in opposite directions .by thepressures within said passageway on.opposite sides of said 'constrictedarea on the one hand and-on opposite sides of said resistance means onthe other hand, thereby ob- .taining afet force due to the ow of thefluid through said passageway, a pressure responsive element adapted toexert a force on said movable element in opposition to said net forceand conduits connecting said pressure responsivemeans y with said airline on opposite sides of said airl valve whereby air pressure anteriorto said air valve will be proportionately effective on said movableelement when saidair valve approaches closed position thereby enrichingthe combustion mixture. l l

. 3. In an apparatus of the class described, pressure responsive means,a lever operatively engaging said pressure responsive means, a hingedfu1- Vcruxn for said lever, means for rotatively adjusting said hingedlever, said lever having an arcuate portion extending circumferentially,and a push rod engageable with said arcuate portion and adapted indifferent rotative positions of said hinge to 'receive a differentproportion of the force exerted by said pressure responsive'means.

4. In apparatus of the character described, condition responsivemeansadapted to exert a force I variable in accordance with the value of saidcondition, movable means associated with said condition responsive meansadapted to beacted upon by said condition responsive means, andacb'ustable meanS interposed between| said condition responsive meansand said movable means, the

'adjustment of said adjustable means providing for transmitting apredetermined proportion of said variable force to said movable member,said adjustable means comprising a lever having an arcuate arm, and asecond arm extending to the. `axis 0f said arcuate arm, and beingadjustable about said axis, said condition responsive means said movablemeans engaging said arcuate arm,

whereby said lever will transmit a reduced or fuel valve, said controlmeans vcomprising pressure responsive means, a conduit providing for aiow of air around said air valve, a regulating valve in said conduit,said pressure responsive means connected to said conduit posterior tosaid regulating valve.

6. A system for controlling combustion of fluid fuel comprising aburner, an air line and a uid nected to said conduit posterior of saidregulating valve. x v

10. A system for controlling combustionv of fluid fuel comprising aburner, an air line anda fluid fuel line Aconnected thereto, a valve insaid air line, a valve in said fuel line, control means for said fuelvalve, said control means comprising engaging said second armadjacentsaid aids, and

pressure responsive means, means for applying a pressure to said`pressure responsive means in accordance with lthe iiow and viscosity'of said fuel, so as to maintain the ilow of\fuel constant irrespectiveof viscosity, means for applying a second pressure to said pressureresponsive means .comprising a conduit connected in parallel to .saidair valve, and' providing for a 4iiow'of air therearound, a pair ofcooperating valves in said conduit spaced to form a chambertherebetween,

' :saidv pressure responsive means operatively connected tosaid'chamber.

`1 1. A system :for controlling lcombustion of uid fuel comprising aburner, an air line and a iiuid fuel line connected thereto, a valve insaid air line, a valve in said fuel line, ccntrolgmeans for said fuelvalve, said control means comprisfuel line connected thereto, a Valve insaid air line, a valve in said' fuel line, control means for said fuelvalve, said control means comprising pressure responsive means, aconduit providing for a fiow of airaround said air valve, a pair ofcooperating valves in said conduit spaced Vto form a chambertherebetween, said pressure responsive means connected to said chamber.

7. A system for controlling combustion of iiuid fuel comprising aburner, an air line and a uid fuel line connected thereto, a valve insaid air line, a valve insaid fuel line, control means for said fuelvalve, said control means comprising pressure responsive means,'aconduit providing for a flow of air around said air valve, a pair ofcooperating valves in said conduit spaced to form a chambertherebetween, said pressure responsive means connected to said chamber,and means for adjusting said cooperating valves to' varytthe pressure insaid chamber.

8. A system for controlling combustion of fluidv fuel comprising aburner, an air line and a iiuid fuel line connected thereto, a valve insaid air line, a valve in said fuel line, control means for said fuelvalve, said control means comprising pressure responsive means, aconduit providing for a ow of air-around said air valve, a pair ofcooperating valves in said conduit spaced to form a chambertherebetween; said pressure responsive means connected to said chamber,and means for simultaneously and oppositely adjusting said cooperatingvalves to vary the pressure in said chamber.

9. A system for controllingv combustion of fluid fuel comprising aburner, an air line" and a fluid fuel line connected thereto, a-,valvein said air vline,'a valve in said fuel line, control Ameans for saidfuel valve, said control means comprising pressure responsive means,means for applying a pressure to saidpressure responsive means inaccordance with the iiow and viscosity of said fuel, so as to maintaintheilow of fuel constant ing pressure responsive means, means forapplying a pressure to said pressure responsive means in accordance withthe ow and viscosity of said fuel, so as to. maintain the iiow of fuelconstant irrespective 'of viscosity, means for applying ya second.pressure to said pressure responsive means comprising a conduitconnected in parallel to said air valve, and providing for aow of airtherearound, a pair of cooperating valves in said conduit spaced to'forma chamber therebetween, said pressure responsive means operativelyconnected to said chamber, and means for adjusting said cooperatingvalves to vary the pressure in said chamber.

12. A system for controlling combustion oi fluid fuel comprising aburner, an air line and a iiuid fuelline connected thereto, a .valve insaid air line, a valve in said fuel line, control means for said fuelvalve, said control means comprising pressure responsive means, meansfor applying a pressureto said pressure responsive means in accordancewith the iiow andviscosity of said fuel, sc as to maintain the now offuel constant irrespective of'viscosity, means for applying a air. line,a valve in said fuel line, control means irrespective of viscosity,-means for applying-a second pressure to said pressure responsive meanscomprising a conduit connected in parallel to said air valve, andproviding for a flow of air therearound, a regulating valve in saidconduit.

said pressure responsive means operatively con second pressure to saidpressureresponsive means comprising a conduit 'connected in parallel tosaid air `valve, and providing for a flow of air therearound, a pair ofcooperating valves in said conduit spaced 4to form a chambertherebetween, said pressure responsive means operatively connected tosaid conduit intermediate said orifices, and means for simultaneouslyand oppositely adjusting said lcooperating valves to vary the pressurein said chamber.

-13'.A system for controlling combustion of fluidvfuel comprising a`burner; an air line and a fluid fuel line connected theretc, a valve insaid for said fuel valve, said control means compris'- ving pressureresponsive means, a conduit providing for a flow cf air around said airvalve, a regulating valve in said conduit, said pressure responsivemeans 'connected to said conduit posterior to said regulating valve, andan adjustable lever connected between said `pressure Yresponsive meansand said fuel valve to vary the eiiectiveness of said pressureresponsive means.

14. Av system for controlling combustion ci fluid fuel comprising aburner, an air line and a fluid fuel line connected thereto, avalve insaid air line, a 'valve in said fuel line, control means 7e for saidfuel valve, said control means compris-y a regulating valve in saidconduit, said pressure responsive means connected to said conduit pos.

terior to said regulating valve, and an adjustable lever connectedbetween said pressure responsive means and said fuel valve to vary theeffectiveness of said pressure responsive means, said lever having anarcuate arm and second arm extending to the axis of said arcuate arm,said lever being adjustable about said axis, said pressure responsivevmeans engaging said second arm adjacent said axis, a member engagingsaid arcuate arm and transmitting a controlling forceto said fuel valve.

,areaaaa l5. A system for controlling combustion of iluid fuelcomprising a plurality of burners, an air supply means including a trunkwith an air valve therein, and 'a branch to-each burner, a fuel supplymeans including a main, a `fuel valve therein, and a branch to eachburner, control means for said fuel valve comprising pressureVresponsive means, a conduit providing a flow of air around saidA airvalve, a regulating valve in said conduit, said pressure responsivemeans con- `nected to said conduit posterior to said regulating valve,and means in at least one of said iluel branches providing a tluidchannel of variable length but of uniform cross section, and means forvvarying the length of said channel.'

HARRY G. GEISSINGER,

